This invention relates to an electronic circuit for generating complex time-varying analog signal waveforms. More particularly, it involves apparatus for simulating electrocardiographic and/or blood pressure waveforms which can be utilized to test remote display devices.
In the above-described application, there is disclosed electronic circuitry for generating time-varying analog signals, preferably representing electrocardiographic and blood pressure waveforms. These waveforms can be coupled to remote display devices to check their operability. A blood pressure monitor, when in actual use, monitors electrical waveforms derived from a transducer sensing the blood pressure of a live patient. The blood pressure monitor provides an excitation signal to the transducer in order to initially energize the transducer. However, different types of blood pressure monitors provide different types of excitation signals, these signals usually being of the pulsed, direct current (DC) or alternating current (AC) type. A simulator device must utilize the excitation signal from the blood pressure monitor. In the above-referenced copending application, there is provided two separate interface circuits, one for a DC excitation signal and one for an AC excitation signal. Unfortunately, this necessitates increased costs for a user who has different types of blood pressure monitors to be checked. For example, a hospital may carry a wide variety of blood pressure monitors which have different types of excitation signals.
In checking the operability of the remote display devices, it is advantageous for the simulator device to simulate waveforms which closely represent the waveforms that would ordinarily be supplied by a live patient. Under true operating conditions, where the patient is being simultaneously monitored by an electrocardiogram machine and a blood pressure monitor, the blood pressure waveform will appear delayed from the electrocardiographic waveform. However, the simulator device of the parent application initiated both simulated waveforms at the same time. While this has provided reliable means for checking the operability of the displays, it would be further advantageous to provide these waveforms in a timed sequence corresponding to the waveforms actually provided by a live patient.
As noted above, it would be advantageous to provide a universal simulator device which is compatible with a wide variety of blood pressure monitors. According to another aspect of this invention, there is provided an interconnection cable which is specifically designed for use with a particular blood pressure monitor. Since each monitor may utilize a particular type of transducer and supply a certain type of excitation signal, complex modifications had heretofore been necessary to make the particular monitor signals compatible with that of a simulator device. To overcome this problem, the interconnection device of the present invention is specifically designed for the particular blood pressure monitor being utilized so as to make its signals compatible with the simulator device. Therefore, the same simulator device can be utilized in conjunction with a variety of different blood pressure monitors merely by changing the cable specifically designed for the monitor under test.